A solar generator is made up of deployable and orientable solar panels. A solar panel is an energy technology device consisting of photovoltaic solar collectors intended to convert solar radiation into electrical energy. On a satellite, the solar generator makes it possible to ensure the input of electrical energy and to make the hardware on board thereof operate. A solar generator can be mounted on a satellite that requires accurate aiming as is the case for a high-resolution observation satellite. The solar panels can exhibit low-frequency vibration modes that are undesirable because they disrupt the control of the line of sight. An observation satellite often aims towards the earth. By contrast, the solar panels do not always see the sun, which poses an energy input problem. To counter this problem it is possible to mount more solar panels on the satellite, but this solution presents the drawback of an excess of weight and bulk, above all upon the launching of the satellite which is contained in the nose cone of the rocket.
There are satellites that can be oriented according to their phase of activity. In observation phase, the satellite is fully oriented towards the Earth's surface, and a reduced solar flux reaches the solar generator. In energy storage phase, the satellite is oriented so that its solar panels are oriented optimally towards the sun, that is to say with the surface normal to the rays. Nevertheless, when the satellite passes over its station on the ground, it is reoriented towards the latter in order to transfer to it the information from its mission. It is therefore difficult to reconcile the observation mission with energy recharging.
Furthermore, the satellite turns its back to the sun and the telescope looks at cold space at a temperature of approximately 3 kelvin, instead of looking towards the earth i.e. towards an environment with a temperature of approximately 10 to 30° C. These situations complicate the regulation and the thermal design of the telescope.
Moreover, when the satellite has its back to the sun, the cavity of the telescope is sometimes facing the “relative wind” linked to the orbital speed. Particles from this environment can erode or deform the internal components of the cavity. Over the required life span of the telescope, it is possible to make the telescope robust to such environmental stresses, but that means a higher demand for telescope quality, thereby implying additional costs.
Some satellites have two articulation arms. One of the arms is situated in the plane of the solar panels and allows for the deployment of the solar panels from the configuration stowed on the satellite to the deployed configuration. The second arm is motorized and makes it possible to orient the generator towards the sun, the second arm being terminated for example by two branches, the arm is linked to the satellite, the two branches are linked to the solar generator. The arm allows for a 360° rotation of the solar generator. Thus, it is possible for the satellite to orient itself so as to aim completely towards the ground and to orient its solar generator towards the sun to ensure the energy input. However, this solution requires the presence of two articulations between the satellite and the solar generator: the articulation dedicated to the deployment of the solar panels and the articulation dedicated to the orientation of the solar generator. This configuration is not optimal for the stiffness of the solar generator: the taking of images must be performed very accurately. The satellite must be able to change attitude, sometimes rapidly, with a good stability and have a high aiming accuracy. The presence of two articulations between the satellite and the solar generator generates a damping problem. In effect, during the change of attitude of the satellite, the solar generator can then be subjected to a first bending mode excited by the manoeuvre of the satellite but uncontrolled by the motorized arm ensuring the orientation of the solar generator. The vibrations then make it difficult to stabilize the aiming.